[PATCH 2/2] perf tools: Prevent calling machine__delete() on non-allocated machine

[Wang Nan <wangnan0@huawei.com>]

To prevent futher commits calling machine__delete() on non-allocated
'struct machine' (which would cause memory corruption), this patch
enforces machine__init(), record whether a machine structure is
dynamically allocated or not, and warn if machine__delete() is called
on incorrect object.

Signed-off-by: Wang Nan <wangnan0@huawei.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Namhyung Kim <namhyung@kernel.org>
---
 tools/perf/tests/vmlinux-kallsyms.c |  4 ++--
 tools/perf/util/machine.c           | 14 +++++++++-----
 tools/perf/util/machine.h           |  3 ++-
 3 files changed, 13 insertions(+), 8 deletions(-)

diff --git a/tools/perf/tests/vmlinux-kallsyms.c b/tools/perf/tests/vmlinux-kallsyms.c
index f0bfc9e..441e93d 100644
--- a/tools/perf/tests/vmlinux-kallsyms.c
+++ b/tools/perf/tests/vmlinux-kallsyms.c
@@ -35,8 +35,8 @@ int test__vmlinux_matches_kallsyms(int subtest __maybe_unused)
 	 * Init the machines that will hold kernel, modules obtained from
 	 * both vmlinux + .ko files and from /proc/kallsyms split by modules.
 	 */
-	machine__init(&kallsyms, "", HOST_KERNEL_ID);
-	machine__init(&vmlinux, "", HOST_KERNEL_ID);
+	machine__init(&kallsyms, "", HOST_KERNEL_ID, false);
+	machine__init(&vmlinux, "", HOST_KERNEL_ID, false);
 
 	/*
 	 * Step 2:
diff --git a/tools/perf/util/machine.c b/tools/perf/util/machine.c
index f5882b8..a2b9b47 100644
--- a/tools/perf/util/machine.c
+++ b/tools/perf/util/machine.c
@@ -23,7 +23,7 @@ static void dsos__init(struct dsos *dsos)
 	pthread_rwlock_init(&dsos->lock, NULL);
 }
 
-int machine__init(struct machine *machine, const char *root_dir, pid_t pid)
+int machine__init(struct machine *machine, const char *root_dir, pid_t pid, bool allocated)
 {
 	map_groups__init(&machine->kmaps, machine);
 	RB_CLEAR_NODE(&machine->rb_node);
@@ -64,6 +64,7 @@ int machine__init(struct machine *machine, const char *root_dir, pid_t pid)
 	}
 
 	machine->current_tid = NULL;
+	machine->allocated = allocated;
 
 	return 0;
 }
@@ -73,7 +74,7 @@ struct machine *machine__new_host(void)
 	struct machine *machine = malloc(sizeof(*machine));
 
 	if (machine != NULL) {
-		machine__init(machine, "", HOST_KERNEL_ID);
+		machine__init(machine, "", HOST_KERNEL_ID, true);
 
 		if (machine__create_kernel_maps(machine) < 0)
 			goto out_delete;
@@ -136,12 +137,15 @@ void machine__exit(struct machine *machine)
 void machine__delete(struct machine *machine)
 {
 	machine__exit(machine);
-	free(machine);
+	if (!machine->allocated)
+		free(machine);
+	else
+		pr_warning("WARNING: delete a non-allocated machine. Skip.\n");
 }
 
 void machines__init(struct machines *machines)
 {
-	machine__init(&machines->host, "", HOST_KERNEL_ID);
+	machine__init(&machines->host, "", HOST_KERNEL_ID, false);
 	machines->guests = RB_ROOT;
 	machines->symbol_filter = NULL;
 }
@@ -162,7 +166,7 @@ struct machine *machines__add(struct machines *machines, pid_t pid,
 	if (machine == NULL)
 		return NULL;
 
-	if (machine__init(machine, root_dir, pid) != 0) {
+	if (machine__init(machine, root_dir, pid, true) != 0) {
 		free(machine);
 		return NULL;
 	}
diff --git a/tools/perf/util/machine.h b/tools/perf/util/machine.h
index 2c2b443..24dfd46 100644
--- a/tools/perf/util/machine.h
+++ b/tools/perf/util/machine.h
@@ -28,6 +28,7 @@ struct machine {
 	pid_t		  pid;
 	u16		  id_hdr_size;
 	bool		  comm_exec;
+	bool		  allocated;
 	char		  *root_dir;
 	struct rb_root	  threads;
 	pthread_rwlock_t  threads_lock;
@@ -131,7 +132,7 @@ void machines__set_symbol_filter(struct machines *machines,
 void machines__set_comm_exec(struct machines *machines, bool comm_exec);
 
 struct machine *machine__new_host(void);
-int machine__init(struct machine *machine, const char *root_dir, pid_t pid);
+int machine__init(struct machine *machine, const char *root_dir, pid_t pid, bool allocated);
 void machine__exit(struct machine *machine);
 void machine__delete_threads(struct machine *machine);
 void machine__delete(struct machine *machine);
-- 
1.8.3.4